The present invention relates to microscopes and more particularly to microscopes having plastic components capable of dissipating static charges.
Conventional stereomicroscopes such as that taught by U.S. Pat. No. 4,690,519, issued Sep. 1, 1987, and compound microscopes such as that taught by U.S. Pat. No. 4,573,771 are used in the manufacture and inspection of semi-conductor components. While earlier examples of such microscopes were manufactured of metal, with the exception of optical components, the industry has substituted plastic for many of the components commonly used in such microscopes. Typical examples of such components are focusing knobs, zoom knobs, eyepiece adjusting rings, and covers for the body, as well as covers for the binocular assembly, all currently made using plastic. However, while numerous different plastics are currently used by various manufacturers and even by single manufacturers, they lack the advantage of being capable of dissipating static charges and place semi-conductor devices and components for such devices at risk of being permanently damaged or rendered useless as a result of exposure to such charges. Semi-conductor devices and components therefor are exposed to such charges, for example, when they are positioned on a microscope stage for inspection. As used herein, the term microscope includes the stand and focusing mechanism of either a compound microscope or stereomicroscope.
U.S. Pat. No. 4,618,222, issued Oct. 21, 1986, describes a protective cover to be positioned between the microscope and stage for supporting the object to be inspected. This patent teaches the need for an antistatic film to be applied to the plastic in order to prevent damage to the components by static charge. The film is then connected to ground.